Dc-dc converter circuit

Abstract

This DC-DC converter circuit includes a switching circuit which switches a DC power supply with a primary side switching element, a transformer to a primary side winding whereof the output of the switching circuit is applied and which outputs a voltage which has been changed by a predetermined voltage change ratio to a secondary side winding, and secondary diodes for current adjustment connected to the secondary side winding of the transformer. Moreover, it includes a regeneration snubber circuit connected in parallel with the secondary diode circuit and including a series circuit of a discharge blocking diode and a snubber capacitor and a switching element for regeneration connected in parallel with the discharge blocking diode, a filter circuit connected between rectification outputs of the secondary diode circuit, and a control unit which turns the switching element for regeneration ON a predetermined time period after the timing of turning the primary side switching element OFF. The predetermined time period is set to approximately the time period during which the charge, accumulated in the snubber capacitor due to reverse recovery time when one of the secondary diodes has been turned OFF, discharges.

Description

TECHNICAL FIELD[0001]The present invention relates to a DC-DC converter circuit which is provided with a secondary side snubber circuit.BACKGROUND ART[0002]A DC-DC converter circuit is provided with a switching circuit which is a primary side switching element and which switches a DC power supply, with a transformer to whose primary side winding the output of said switching circuit is supplied and which outputs at its secondary side winding a voltage which has been changed by a predetermined voltage change ratio, and a secondary diode for current adjustment which is connected to the secondary side winding of said transformer. Having been rectified by the secondary diode, the output is supplied to a load after being smoothed.[0003]However since, when it is turned off, due to accumulated carriers, the secondary diode has a time period trr in which it can conduct current (this time period is termed the reverse recovery time, or the recovery time), accordingly a through current flows in...

AI Technical Summary

Benefits of technology

[0013]Since, according to this invention, the energy which is accumulated in the leakage inductance due to the through current component flowing in the secondary winding when the secondary diode is turned off is regenerated to the load, accordingly no surge voltage is applied to the secondary diode, and moreover the efficiency is enhanced, since there is no heat loss.

Problems solved by technology

However since, when it is turned off, due to accumulated carriers, the secondary diode has a time period trr in which it can conduct current (this time period is termed the reverse recovery time, or the recovery time), accordingly a through current flows in the secondary winding of the transformer during this reverse recovery time, and, due to this, there is the problem that a surge voltage is applied to the rectification element when it has been turned off.

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